Aeroplane with three centers of propulsion arranged in a triangle



" July 31, 1928.

1,679,038 s. F. w. KOOLHOVEN AEROPLANE WITH THREE CENTERS OF PROPULSION ARRANGED IN A TRIANGLE Filed March 1926 Patented July 31, 1928.

UNITED STATES PATENT OFFICE.

SYTSE FREDERICK WILLEM KOOLHOVEN, OF RIJSWIJK, NETHERLANDS.

AEROPLANE WITH THREE CENTERS 0F PROPULSION ARRANGED IN .A TRIANGLE.

Application filed March 4, 1926, Serial No. 92,294, and in the Netherlands September 5, 1924.

The invention relates to aeroplanes with three centers of propulsion arranged in a triangle, the expression center of propulsion signifying a place, or a point, where one or more elements are arranged, which influence at that place the surrounding air in such a way that a propelling force is exerted on the aeroplane. A center of propulsion is therefore a 'place, whe re for instance a single screw or propeller or a compound screw or propeller, or one or more screws, propellers etc. placed in tandem are arranged.

According to the invention the center of propulsion interposed between the two other.

ones is located above the body, the corresponding screw or screws (propellers) being made and arranged in such a way that in the normal flying position the area bounded by the circle of rotation of the screw or screws or propellers in question is either notor at most 30% overlapped by the vertical projection of the body. With vertical pro jection is meant the projection on a vertical plane.

This arrangement results in that none of the three screws orpropellers need operate in front of the plane of the body, which was the case with the aeroplanes with three screws or propellers known up to now. The efficiency of the screws is thereby considerably increased and the resistance of the body decreased. Another advantage is that the three slip currents are entirely separated from each other, which renders impossible the occurrence of interference-phenomena.

' The three power supplying engines are according to this invention arranged freely accessible, which facilitates eventual repair.

An embodiment of the invention is illustrated with reference to the annexed diagrammatical drawing.

In the drawing is: Fig. 1 a front view and Fig. 2 a side elevationof the aero lane,

in which for the sake of clearness alletails of no importance for a good understanding of the invention are omitted- V For simplicitys sake only the word screw or propeller has been used. It will, however,

be clear that this expression covers also the operative elements of centers of propulsion in the broadest scope, consequently screws or propellers placed in tandem, compound screws, etc.

1 indicates the body, 2 the screw or propeller interposed between the two other ones, 3 and 4 respectively are the left and the right screw or propeller. In Fig. 1 only the circles of rotation of the screws are indicated. 5 are the connecting points of the wing 6 to the body. As appears from F ig.

1, the circle of rotation of the screws interposed between the two other ones isin this embodiment not overlapped by the vertical projection of the body. The center of propulsion placed between the two other ones is arranged above the body. Preferably the engine interposed between the two other ones is secured to the body with a resilient intermediate layer, e. g. by movably mounting the supports 7 on rods 9 attached in lugs 8, blocks 10 of hard rubber, being interposed.

In contradistinction to the usual construction the vibrations of the engine are not directly transmitted to the body. Moreover the noise of the exhaust cannot easily penetrate into the cabin owing to the fact that the wing is located between exhaust and cabin. This considerably contributes to the comfort of the passengers in the cabin. This is of great importance especially for passenger tralfic.

I claim I A monoplane comprising a body, a single wing positioned at the upper side of the body, and only three centers of propulsion arranged in a triangle, one of .said centers of propulsion only, interposed'between the other two centers'of propulsion, being lo-.

cated above the body of the aeroplane above SYTSIZ FREDERICK WILLEM KQOLIIOVHN; 

